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# C Library Function - ferror() [ C Standard Library - ](#) ## Description The C library function **int ferror(FILE *stream)** tests the error indicator for the given stream. ## Declaration Below is the declaration for the ferror() function. int ferror(FILE *stream) ## Parameters * **stream** -- This is a pointer to a FILE object that identifies the stream. ## Return Value If the error indicator associated with the stream was set, the function returns a non-zero value, otherwise, it returns a zero value. ## Example The following example demonstrates the usage of the ferror() function. #include int main(){ FILE *fp; char c; fp = fopen("file.txt", "w"); c = fgetc(fp); if( ferror(fp) ) { printf("Error reading from file: file.txtn"); } clearerr(fp); if( ferror(fp) ) { printf("Error reading from file: file.txtn"); } fclose(fp); return(0);} Let us assume we have a text file **file.txt**, which is an empty file. Let us compile and run the above program, as we are trying to read from a file opened in write-only mode, this will produce the following result. Error reading from file: file.txt [ C Standard Library - ](#)